Feed material, such as silage, is frequently stored in a hermetically sealed storage structure or silo, and the stored material is removed from the structure by a bottom unloader. The conventional bottom unloader, as disclosed in U.S. Pat. No. 2,635,770, takes the form of a cutter arm which is mounted for rotation about the center of the silo and carries an endless cutter chain having a plurality of hook-shaped cutter teeth. The chain travels in an endless path on the cutter arm. As the arm sweeps around the bottom of the structure, the cutter teeth on the chain cut through and dislodge the stored material and convey the dislodged material to a trough located in the floor of the structure. A conveyor mounted in the trough then conveys the dislodged material through the trough to the exterior of the structure.
The conventional cutter teeth have a hook-like configuration, including a relatively thin body having a sharp leading edge and an outer, enlarged, diamond shaped head. In the past, the cutter teeth have been mounted in a random arrangement on the chain with some of the teeth projecting laterally outward from the chain, other teeth projecting upwardly and outwardly from the chain, while still other teeth projected upwardly and inwardly over the chain.
It has been found that chopped grass, lacking heavy stems or stalks, compacts very tightly in a storage structure, producing a dense and hard packed mass. Because of the densely packed nature of grass material, the delivery rate of the conventional bottom unloader is substantially reduced, as opposed to the delivery rate of a coarser material such as silage. As the delivery rate is reduced, the time required to deliver a given quantity of grass from the structure is considerably greater than the time required to deliver an equal amount of silage.